Helical head comminuting shear

Abstract

A cutting machine to sever elongated wood particles or fiber masses to a predetermined length in one self-feeding and continuous operation. Said cutting machine reduces naturally formed and partially processed wood into particles of controlled length and cross-sectional dimension. A rotating spiral cutting edge mounted on a drive shaft is of varying radial length increasing from zero on one end to a radial length greater than the cross-sectional dimension of the wood or fiber to be sheared. In back of the shearing section a separate degradation spiral is situated that gradually decreases back to a minimal radial length on the other end. An anvil is provided over the length of the shearing section against which the rotating cutting edge shears the wood. In the back or degradation section, a casing in the shape of a truncated cone is fitted loosely around the decreasing spiral. Wood is fed parallel to the drive shaft into the front end of the apparatus. The rotating cutting edge contacts the log at regular intervals, thus severing wood particles of close length tolerance which are carried by the degradation spiral section and then pass through the degradation cone where, due to decreasing diameter and positive feed, cross-sectional area of said particles are reduced by longitudinal splitting and abrasion to permit passage through the outer end of the truncated cone.